Biogen: Tecfidera link to MS patient's death 'unlikely'

A woman who had used Biogen Idec's new multiple sclerosis pill Tecfidera has died, and the company is investigating the case. She was suffering from a form of pneumonia that tends to afflict MS patients, The Wall Street Journal notes, and Biogen says it's "unlikely" that Tecfidera caused her death.

The patient had stopped taking Tecfidera about two-and-a-half weeks before her death because of gastrointestinal side effects. She had been using the drug for a little over 5 weeks at the time. The company ($BIIB) learned of her death last week.

Biogen says it's still actively investigating the case. "Biogen Idec is committed to patient safety, and it continues to be our first priority," a spokeswoman told the WSJ.

A highly anticipated addition to the MS treatment arsenal, Tecfidera hit the market earlier this year and has been going gangbusters ever since. It's not uncommon for safety worries to arise as a new drug is rolled out to the general patient population, typically a more diverse group than the subset selected to participate in clinical trials. So far, this case doesn't appear to bear the hallmarks of a brewing safety concern, however; as ISI Group analyst Mark Schoenebaum said in an investor note, "I see this as a non-issue."

When serious side effects multiply, sales can suffer, even if those side effects were predicted in pre-approval studies. Consider Gilenya, the Novartis ($NVS) pill that competes directly with Tecfidera; after it made its debut, a cardiac risk flagged in clinical trials cropped up in some patients, and one died soon after his first dose. The FDA put the drug under review.

Later, the agency recommended label changes warning doctors to perform an electrocardiogram (ECG) before each patient starts therapy and to keep new patients under surveillance for 6 hours after their first doses. FDA also recommended against using Gilenya in patients with a history of stroke or certain heart problems. After the safety issues arose, analysts trimmed their sales estimates, but figured that Gilenya would get back on a growth track soon enough.

What's more, MS drugs in general tend to suppress the immune system, making patients more prone to infection. Biogen said the patient in this case had a history of irritable bowel disease and infections such as bronchitis, the WSJ reports. Biogen hasn't said whether this patient had been treated with other MS therapies before starting on Tecfidera.